Power in meetings may be enacted in many ways, ranging from democratic and collaborative through to authoritative and didactic, with the exact positioning on this continuum typically under the control of the chair. By contrast with the focus of most previous research on the behaviour of institutionally ratified chairs of intact teams, this paper examines how volunteer chairs of small focus groups in public meetings use the power associated with that role to manage the discussion and to encourage or discourage explicit expression of disagreement. Our analysis identifies ways in which these arbitrarily assigned chairs influence and facilitate the small group discussions through a range of discourse practices. By separating the chair role from its typical co-occurrence with institutional hierarchy we are able to demonstrate the inherent influence and power of the position in the decision making process.